KR20100034612A - Method for fabricating flash memory device having 3-dimensional structure - Google Patents

Abstract

PURPOSE: A manufacturing method of the flash memory device of three dimensional structure embodies the memory cell about the semiconductor substrate as the vertical direction. The degree of integration of the memory cell is multiplied in the substrate area without limit. CONSTITUTION: Area-source is formed in the substrate(300). In the top of the substrate, the source selection transistor connected to area-source is formed. The insulating layer and conductive layer are formed by turns on outcome and the gate(420) of a plurality of memory cells is formed. The penetration hole in which the insulating layer and conductive layer are etched and exposing the channel region(370) of the source selection transistor is formed. The charge storage region(440) consisting of the tunneling layer in the inner wall of the penetration hole, and the charge trapping layer and blocking layer is formed.

Description

Method for fabricating flash memory device having three-dimensional structure {Method for fabricating flash memory device having 3-dimensional structure}

The present invention relates to a method for manufacturing a flash memory device, and more particularly, to a method for manufacturing a flash memory device having a three-dimensional structure.

In general, semiconductor memory devices used to store data can be classified into volatile memory devices and non-volatile memory devices. Volatile memory devices lose their stored data when their power supplies are interrupted, while nonvolatile memory devices retain their stored data even when their power supplies are interrupted. Thus, such as in mobile phone systems, memory cards and other applications for storing music and / or video data, nonvolatile memory devices in situations where power is not always available, often interrupted, or where low power usage is required. Is widely used. A typical example of such a nonvolatile memory device is a flash memory device capable of batch erasing.

With the miniaturization and light weight of electronic devices, the demand for smaller size cells is increasing even in the case of flash memory devices. However, in the current two-dimensional cell structure in which memory cells are formed as a single layer on a semiconductor substrate, the degree of integration of the memory cells is determined by the limitations of the patterning technology and the packaging technology. In order to overcome the limitations of the packaging technology, the line width of the device has been continuously reduced to increase the density of the memory device. However, as the patterning technology reaches a certain limit, the integration of memory devices is limited, and it is difficult to meet these demands with the current two-dimensional cell structure in a situation that demands continuous increase in the market.

In order to improve the disadvantage of the two-dimensional structure, the proposed structure is a three-dimensional cell structure. The three-dimensional cell structure is largely divided into a structure in which the same two-dimensional structure is stacked on top of the present, and a channel is formed in a vertical direction with the silicon substrate, unlike the existing concept. However, in the case of stacking the same two-dimensional structure on top of the present, there is a limitation in increasing the degree of integration, and in the case of forming a channel in a vertical direction with the silicon substrate, the cell structure is formed of a depletion transistor structure and the wells are formed. Since it is not formed, since the hole injection method is formed by hot hole formation rather than conventional FN tunneling during the erasing operation, it is difficult to implement more than a certain degree of integration.

An object of the present invention is to provide a method of manufacturing a flash memory device having a structure that can increase the degree of integration of the memory cell without being limited to the substrate area by implementing the memory cell in a vertical direction with respect to the semiconductor substrate.

Another object of the present invention is to provide a method of manufacturing a flash memory device having a structure in which memory cells arranged in a vertical direction on a substrate can be erased by FN tunneling, which simultaneously erases the entire string instead of a hot hole injection method. There is.

In order to achieve the above technical problem, a method of manufacturing a flash memory device according to the present invention includes forming a source region on a substrate, forming a source select transistor connected to the source region on the substrate, and forming a source select transistor. Forming a plurality of gates of a plurality of memory cells by alternately forming an insulating layer and a conductive layer on the substrate, and forming a through hole exposing the channel region of the source selection transistor by etching the insulating layer and the conductive layer. And forming a charge storage region including a tunneling layer, a charge trap layer, and a blocking layer on an inner wall of the through hole, forming a protective film on an inner sidewall of the through hole where the charge storage region is formed, and a channel region of the source selection transistor. Exposing the through holes to the semiconductor layer to form a channel region of the cell transistor; , And it is characterized in that it comprises a step of forming a drain select transistor to the cell transistor.

The forming of the source selection transistor may include sequentially stacking an insulating layer and a conductive layer on the substrate, forming a through hole for exposing the source region by etching the insulating layer and the conductive layer; Forming a gate insulating film on an inner wall of the through hole, etching the gate insulating film to expose the source region, and forming a channel region of a source selection transistor by filling the through hole with a semiconductor layer. .

The protective film may be formed of a polysilicon film or a nitride film.

The protective layer may be removed before the through hole is filled with the semiconductor layer.

The conductive layer for forming the gate of the memory cell may be formed of polysilicon or a metal.

In the forming of the tunneling layer, the silicon compound may be deposited in an atmosphere containing oxygen or oxygen and nitrogen.

After the forming of the tunneling layer, the method may further include heat treatment in an NO or N ₂ O atmosphere.

According to another aspect of the present invention, there is provided a method of manufacturing a flash memory device, including: forming a source region on a substrate, forming an insulating layer and a conductive layer on the substrate, and exposing the source region; Forming a through hole, sequentially forming a gate insulating film and a channel region of a source selection transistor on sidewalls of the first through hole, forming a well in a source region of a region exposed by the first through hole; Forming a well of the source select transistor by filling the first through hole, and alternately forming an insulating layer and a conductive layer on the substrate on which the well of the source select transistor is formed to form gates of a plurality of memory cells Forming a second through hole through which the insulating layer and the conductive layer are etched to expose the channel region of the source select transistor; and an inner wall of the second through hole. Forming a charge storage region consisting of a tunneling layer, a charge trap layer and a blocking layer, etching the charge storage region at the bottom of the second through hole to expose the channel region of the source select transistor, and etching the inner wall of the second through hole. Forming a channel region of the memory cell, forming a well of the cell transistor by filling a second through hole, and forming a drain select transistor on the cell transistor.

Forming a well in a source region of a region exposed by the first through hole may include opening a region in which a well of a source select transistor is to be formed, and doping the opened region in an opposite conductivity type to the source region. It may include.

In the step of doping the open region to the opposite conductivity type to the source region, a dopant of the opposite conductivity type to the source region may be implanted into the open region, or the substrate of the open region may be overetched.

The forming of the well of the source selection transistor may include forming a silicon layer of a first conductivity type or by doping by implanting a dopant of a first conductivity type after depositing an undoped silicon layer.

In the forming of the tunneling layer on the inner wall of the second through hole, the silicon compound may be deposited in an atmosphere containing oxygen or oxygen and nitrogen. After the forming of the tunneling layer, the method may further include heat treatment in an NO or N ₂ O atmosphere.

After forming the charge storage region on the inner wall of the second through hole, the method may further include forming a protective film on the inner wall of the second through hole in which the charge storage region is formed.

The protective film may be formed of a polysilicon film or a nitride film.

The forming of the well of the cell transistor may include forming a silicon layer of a first conductivity type or by doping by implanting a dopant of a first conductivity type after depositing an undoped silicon layer.

According to the present invention, the degree of integration of the flash memory device can be increased by arranging the memory cells in a vertical direction from the semiconductor substrate. In addition, by forming wells in vertically arranged memory cells, data of the memory cells may be simultaneously erased by F-N tunneling.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, embodiments of the present invention may be modified in many different forms, and the scope of the present invention should not be construed as limited by the embodiments described below.

1 is a three-dimensional view showing a flash memory device having a three-dimensional structure according to an embodiment of the present invention.

Referring to FIG. 1, a flash memory device having a three-dimensional structure according to an embodiment of the present invention may include a source select transistor formed on a substrate 100, a source select transistor formed on the source select transistor, and an insulating layer 210. The gate stacks 220 repeatedly stacked so as to be separated from each other, a charge storage region 240 formed of a blocking layer, a charge trap layer, and a tunneling layer formed on sidewalls of the through-holes through the gate stacks, and the through-holes. Memory cells including the channel region 260 formed therein, and a drain select transistor formed to be connected to the memory cell.

The source select transistor, the plurality of memory cells, and the drain select transistor are arranged vertically on the substrate 100 to form a single cell string, and a plurality of such cell strings are disposed on the substrate 100.

The source selection transistor may include a gate conductive layer 130 formed on the substrate 100 to be separated by the insulating layers 120 and 140, and a through hole penetrating through the gate conductive layer 130 and the insulating layers 120 and 140. The gate insulating layer 160 is formed on the inner wall, and the channel region 170 is formed to fill the through hole in which the gate insulating layer is formed. The channel region is connected to the source 110 formed in the substrate 100. The channel region 170 may be formed of a silicon epitaxial layer, or may have a structure in which a silicon epitaxial layer and a polysilicon layer are sequentially stacked from sidewalls of the gate insulating layer in the through hole.

The gate stack 220 constituting the memory cell is repeatedly stacked as many as the number of memory cells connected to one cell string. The memory cells connected to one cell string are separated by the insulating layer 210, and the memory cells arranged on the same layer constitute one page.

The drain select transistor has the same structure as the source select transistor, and the channel region 310 is connected to the channel region 260 of the memory cell.

2 to 11 are cross-sectional views illustrating a method of manufacturing a flash memory device having a three-dimensional structure according to an embodiment of the present invention. The same reference numerals as in FIG. 1 denote the same parts.

Referring to FIG. 2, an impurity layer 110 for forming a common source of cells is formed on the substrate 100. The substrate 100 may be a single crystal silicon (Si) substrate doped with a P-type impurity. The impurity layer 110 may be formed by ion implantation of an impurity of an opposite conductivity type, for example, N type, into the semiconductor substrate 100. Next, in order to define the common source region, the impurity layer 110 and the semiconductor substrate 100 in regions other than the source are etched using a photolithography process. An insulating layer 120 is deposited on the resultant to separate the impurity layer from other conductive layers.

Referring to FIG. 3, a conductive layer 130 for forming a gate of a selection transistor on a substrate on which an insulating layer 120 is formed, and an insulating layer 140 for separating the conductive layer and a conductive layer formed thereon. Form in turn. The conductive layer 130 may be formed of a polysilicon layer doped with an impurity, a metal such as tungsten (W), or another conductive material to a thickness of about 10 to about 1,000 μm.

Next, a hole 150 exposing the impurity layer 110 formed in the substrate 100 by etching the conductive layer 130 and the insulating layer 140 in the region where the channel of the source select transistor is to be formed. To form. The hole 150 is a region in which a channel of the source select transistor is formed, and is formed to have a diameter of 10 to 1,000 kHz. The etching process for forming the hole 150 may be performed by wet etching, dry etching, or a mixture thereof.

Referring to FIG. 4, a gate oxide layer 160 of a source select transistor is formed by depositing, for example, a silicon oxide layer on a side of the hole to a thickness of about 10 to about 500 microseconds. When the gate insulating layer 160 is formed, oxidation may be performed in an atmosphere containing oxygen and nitrogen at the same time to form an oxynitride layer (SiON). In addition, after the gate insulating film 160 is formed, the film quality of the gate insulating film may be improved by heat treatment in an NO gas or N ₂ O gas atmosphere.

Next, an inside of the hole in which the gate insulating layer 160 is formed is filled with a semiconductor layer such as single crystal silicon (Si). The semiconductor layer may be formed using, for example, a selective epitaxial growth (SEG) method such that the silicon (Si) film is selectively grown from the impurity layer 110 in a gas atmosphere including silicon (Si), and is selected. Becomes the channel region 170 of. In this way, a source select transistor including the channel region 170, the gate insulating layer 160, and the conductive layer 130 as the gate electrode is formed.

Referring to FIG. 5, the interlayer insulating film 210 and the conductive layer 220 are repeatedly deposited several times on the resultant material on which the source select transistor is formed. The interlayer insulating layer 210 is used to separate the memory cells stacked vertically, and may be formed of a silicon oxide film, a silicon nitride film, or a stacked film of a silicon oxide film and a silicon nitride film. The conductive layer 220 may be formed by, for example, depositing a polysilicon film, a polysilicon germanium film, a metal film, or another conductive material with a thickness of 10 to 1,000 Å doped with P-type impurities. The conductive layer 220 may be repeatedly stacked up to the number of memory cells connected to one cell string, for example, twice, four times, eight times,..., 1,000 times. The conductive layer 220 becomes a control gate of the memory cell, and the interlayer insulating layer 210 serves to separate the memory cells stacked vertically.

Referring to FIG. 6, after stacking the conductive layer 220 and the interlayer insulating film 210 by the number of memory cells connected to the cell string, the through-holes are formed to form ONO films for channel and charge storage of the cell transistors. 230). In detail, the conductive layers 210 and the interlayer insulating layer 220 stacked alternately are anisotropically etched to expose the gate insulating layer 160 and the channel region 170 of the source selection transistor. In this case, the etching process may use a wet or dry etching method, and the through hole 230 may have a size that may be gap-filled with a semiconductor layer serving as a channel of a cell transistor and an ONO film serving as a charge storage layer. . In this embodiment, the through hole 230 is formed to a diameter of 10 ~ 1,000Å.

Referring to FIG. 7, an ONO dielectric layer 240, that is, a blocking layer, a charge trap layer, and a tunneling layer, may be sequentially formed on the inner wall of the through hole 230.

Specifically, a blocking layer is formed on the inner wall of the through hole 230 to prevent the transfer of charge from the charge trap layer (not shown) to the control gate electrode. The blocking layer is formed by depositing an oxide film by chemical vapor deposition (CVD), or by using aluminum oxide (Al ₂ O ₃ ), hafnium oxide (HfO ₂ ), zirconium oxide (ZrO ₂ ), hafnium aluminum oxide (HfAlO), and hafnium silicon. It may be formed of a high-k material such as oxide (HfSiO). After the blocking layer is formed, a rapid thermal annealing process may be performed on the semiconductor substrate on which the blocking layer is formed.

Next, a charge trap layer is formed by depositing, for example, a silicon nitride film or a polysilicon film on the blocking layer formed on the inner wall of the through hole 230 to a thickness of 10 to 1,000 占 퐉. The charge trap layer may be deposited by atomic layer deposition (ALD) or chemical vapor deposition (CVD). An oxide film is deposited to a thickness of 10 to 1,000 Å on the charge trap layer of the inner wall of the through hole 230 to form a tunneling layer of the memory cell. When forming the tunneling layer may be performed in an atmosphere containing oxygen and nitrogen at the same time to form an oxynitride (SiON). In addition, after the tunneling layer is formed, the film quality of the tunneling layer may be improved by heat treatment in an NO gas or N ₂ O gas atmosphere.

Referring to FIG. 8, a passivation layer 250 is formed on the tunneling layer formed on the inner wall of the through hole to protect the ONO dielectric layer 240 in the subsequent etching of the ONO dielectric layer. The protective film 250 may be formed of a conductive film such as a doped polysilicon film or an insulating film such as a nitride film, and has a thickness of 10 to 1,000 Å. When the passivation layer 250 is formed of a conductive layer such as a doped polysilicon layer, the passivation layer 250 may be used as a channel region or a part of the channel region of the memory cell.

In order to connect the channel region of the source select transistor with the channel region of the memory cell, the passivation layer 250, the tunneling layer, the charge trap layer, and the blocking layer at the bottom of the through hole are etched to expose the channel region 170 of the source select transistor. . Since the passivation layer 250 having an etch selectivity with respect to the dielectric layer is formed on the side surface of the ONO dielectric layer 240, the etching or etching damage of the dielectric layer does not occur during the etching process for the dielectric layer.

Referring to FIG. 9, the channel material 260 of the cell transistor is formed by depositing a conductive material so that the through-holes are filled on a result of exposing the channel area of the source selection transistor. The channel region 260 of the cell transistor may be formed of a polysilicon film or a conductive metal film doped with impurities. The protective film formed on the sidewall of the ONO dielectric layer may be removed before the channel region is formed. In this embodiment, after removing the protective film, the channel region is formed. Meanwhile, when the protective film on the ONO dielectric layer 240 is formed of a conductive film such as a doped polysilicon film and used as a channel of a memory cell, the through hole in which the protective film is formed may be filled with an insulating film such as an oxide film or a nitride film. As a result, the source select transistor and the plurality of memory cells separated by the insulating layers 140 and 210 are formed from the substrate 100.

Referring to FIG. 10, a drain select transistor for string selection is formed on a resultant product in which a plurality of memory cells are formed.

In detail, an insulating layer 270 for separating the drain selection transistor and the uppermost memory cell is formed on the resultant through-hole to fill the channel region of the memory cell. A doped polysilicon film, a metal film, or another conductive material film is formed on the insulating film 270 to a thickness of 10 to 1,000 Å to form a conductive layer 280 for forming a gate of the drain select transistor. Subsequently, an insulating film 290 is formed to separate the gate conductive layer 280 of the drain select transistor from the upper conductive layer.

Next, in order to connect the drain selection transistor and the memory cell transistor, the conductive layer 280 and the insulating layers 270 and 290 are anisotropically etched to form holes. The etching process for forming the hole may be performed by wet etching, dry etching, or a mixture thereof. The hole is formed to have a diameter of 10 to 1,000 ,, and the channel region 260 of the ONO dielectric layer and the memory cell is exposed as shown.

Referring to FIG. 11, a silicon oxide film is deposited on the inner wall of the hole formed so that the ONO dielectric layer 240 and the channel region 260 of the memory cell are exposed to have a thickness of about 10 to 500 kV, for example, to form a gate insulating film of the drain select transistor. 300). When the gate insulating film 300 of the drain selection transistor is formed, the oxygen oxynitride film SiON may be formed in an atmosphere containing oxygen and nitrogen at the same time. In addition, after the gate insulating film 300 is formed, the film quality of the gate insulating film may be improved by heat treatment in an NO gas or N ₂ O gas atmosphere.

Next, in order to connect the channel region of the memory cell and the channel region of the drain select transistor, the gate insulating layer 300 at the bottom of the hole is etched to expose the channel region of the memory cell. Before etching the gate insulating film 300, a protective film made of a conductive film such as a polysilicon film is formed on the gate insulating film 300 formed on the inner wall of the hole and then etched to protect the gate insulating film 300 on the sidewall of the hole. Can be. In this case, the conductive film used as the passivation film may be used as a channel region or a part of the channel region of the drain select transistor.

The semiconductor layer is formed to fill the hole on the result of exposing the channel region of the memory cell to form the channel region 310 of the drain select transistor. The semiconductor layer may be formed using, for example, a selective epitaxial growth (SEG) method so that the silicon (Si) film is grown from the channel region of the memory cell in a gas atmosphere containing silicon (Si). Meanwhile, when the protective layer on the gate insulating layer is formed of a conductive layer such as a doped polysilicon layer and used as a channel of the memory cell, the contact hole may be filled with an insulating layer such as an oxide layer or a nitride layer. Next, an etching process for separating the drain select transistors is performed.

According to one embodiment of the present invention, by stacking memory cells vertically from a semiconductor substrate, the degree of integration of the memory device can be dramatically increased regardless of the area of the substrate and the patterning limit. In addition, by forming an ONO dielectric layer, which is a charge storage region of the memory cell, and then forming a passivation layer, an etch or etch damage of the ONO dielectric layer is etched during the etching of the ONO dielectric layer in order to connect the channel region of the memory cell to the channel region of the source select transistor. By preventing the deterioration of the characteristics of the flash device can be prevented.

12 and 13 are three-dimensional views showing a flash memory device having a three-dimensional structure according to another embodiment of the present invention.

12 and 13, a flash memory device having a three-dimensional structure according to another exemplary embodiment of the present invention may include a source select transistor formed on a substrate 300, a source select transistor formed on the source select transistor, and an insulating layer 410. Gate stacks 420 repeatedly stacked so as to be separated by a plurality of layers), a charge storage region 440 comprising a blocking layer, a charge trap layer, and a tunneling layer formed on sidewalls of the through holes penetrating the gate stacks, and in the through holes. Memory cells including a channel region 460 formed on the charge storage region 440, a through hole in which the channel region is formed, and a well region 470 opposite to the channel region. And a drain select transistor formed to be connected to the memory cell.

As in the case of the first embodiment shown in FIG. 1, a source select transistor, a plurality of memory cells, and a drain select transistor are arranged vertically on the substrate 300 to form a cell string, and memory cells arranged in the same layer. They constitute a page. The source select transistor penetrates through the gate conductive layer 330 formed to be separated by the insulating layers 320 and 340 on the substrate 300, and passes through the gate conductive layer 330 and the insulating layers 320 and 340. The gate insulating layer 360 formed on the inner wall of the hole, the channel region 370 formed on the sidewall of the gate insulating layer, and the well region 380 formed to fill the through hole in which the channel region is formed. The channel region of the source select transistor is connected to the source 310 formed in the substrate 300, and is formed of a silicon epitaxial layer, or a silicon epitaxial layer and a polysilicon layer are sequentially stacked from sidewalls of the gate insulating layer in the through hole. Made of structure.

The gate stack 420 constituting the memory cell is repeatedly stacked as many as the number of memory cells connected to one cell string. The memory cells connected to one cell string are separated by an insulating layer 410. Well regions 380 and 470 doped with a conductive type opposite to the channel region, for example, a P-type dopant, are disposed in the channel region of the source select transistor and in the channel region of the memory cell. The well regions 380 and 470 are for temporarily pulling out the charges trapped in the charge trap layer of the memory cell. In the conventional charge trapping flash device, since the data cannot be erased by F-N tunneling, the data is erased by a hot electron injection (HEI) method. However, in the case of the present invention, by temporarily extracting the charges stored in the charge trap layer of the memory cell into the well region 470 and injected into the well region 380 of the source select transistor to temporarily erase, which is an advantage of the flash memory device. Becomes possible.

In the case of the drain select transistor, the string selection function may be performed, and thus the well selection region 530 may be provided as shown in FIG. 13, or may not include the well region as illustrated in FIG. 12.

14 to 20 are cross-sectional views illustrating a method of manufacturing a flash memory device having a three-dimensional structure according to another embodiment of the present invention.

Referring to FIG. 14, an impurity layer 310 for forming a common source of cells is formed on the substrate 300. The substrate 300 may be a single crystal silicon (Si) substrate doped with P-type impurities. The impurity layer 310 may be formed by ion implantation of an impurity of a conductivity type, for example, N type, with the substrate 100. Next, in order to define the common source region, the impurity layer 310 and the substrate 300 in regions other than the source are etched using a photolithography process. The insulating layer 320 is deposited on the resultant to separate the source region from other conductive layers.

A conductive layer 330 for forming a gate of the selection transistor and a insulating layer 340 for separating the conductive layer and the conductive layer formed thereon are sequentially formed on the substrate on which the insulating layer 320 is formed. The conductive layer 330 may be formed of a polysilicon layer doped with an impurity, a metal such as tungsten (W), or another conductive material to a thickness of about 10 to about 1,000 mm 3.

Next, the conductive layer 330 and the insulating layer 340 in the region where the channel of the source select transistor is to be formed are etched to form a hole 350 exposing the impurity layer 310 of the substrate. The hole 350 is a region in which a channel of the source select transistor is formed and is formed to have a diameter of 10 to 1,000 Å. The etching process for forming the hole 350 may be performed by wet etching, dry etching, or a mixture thereof.

Referring to FIG. 15, a gate oxide film 360 of a source select transistor is formed by depositing a silicon oxide film on a side of the hole, for example, in a thickness of 10 to 500 占 퐉. When the gate insulating layer 360 is formed, the gate insulating layer 360 may be formed in an atmosphere containing oxygen and nitrogen at the same time to form an oxynitride layer (SiON). In addition, after the gate insulating film 360 is formed, the film quality of the gate insulating film may be improved by heat treatment in an NO gas or N ₂ O gas atmosphere.

Next, a semiconductor layer such as single crystal silicon (Si) is formed in order to form a channel of the source select transistor on the side of the hole in which the gate insulating film 360 is formed. The semiconductor layer is formed of a silicon layer doped with an opposite conductivity type, for example, N-type, to the substrate 300. The semiconductor layer may be formed using, for example, a selective epitaxial growth (SEG) method so that the silicon (Si) film is grown from the impurity layer 310 in a gas atmosphere including silicon (Si), and may be a channel of a selection transistor. Area 370. In this case, unlike the case of the first embodiment, the semiconductor layer is formed only on the sidewalls of the holes to form the P-well in the center of the holes, rather than filling the holes with the semiconductor layers.

Next, in order to connect the P well formed in the source select transistor region to the substrate, a P type impurity is implanted through a hole to dope the impurity layer 310 below the well to a P type or The P-type substrate is exposed by over-etching the impurity layer 310 exposed through the semiconductor layer. Next, the center of the hole is filled with a P-type silicon layer to form a P well 380 for connecting with the P well of the memory cell.

Referring to FIG. 16, the interlayer insulating film 410 and the conductive layer 420 are repeatedly deposited several times on the resultant formed source select transistor. The interlayer insulating film 410 is used to separate memory cells stacked vertically, and may be formed of a silicon oxide film, a silicon nitride film, or a stacked film of a silicon oxide film and a silicon nitride film. The conductive layer 420 may be formed by, for example, depositing a polysilicon, a polysilicon germanium film, a metal film, or another conductive material with a thickness of 10 to 1,000 Å doped with a P-type impurity. The conductive layer 420 may be repeatedly stacked as many as the number of memory cells connected to one cell string. The conductive layer 420 serves as a control gate of the memory cell, and the interlayer insulating layer 410 separates the memory cells stacked vertically.

After stacking the conductive layer 420 and the interlayer insulating layer 410 as many as the number of memory cells connected to the cell string, a through hole 430 is formed to form an ONO film for channel and charge storage of the cell transistor. In detail, the conductive layers 410 and the interlayer insulating layer 420 that are alternately stacked are anisotropically etched to expose the gate insulating layer 360 and the channel region 370 of the source selection transistor. In this case, the etching process may use a wet or dry etching method, and the through hole 430 may have a size that can be gap-filled with the semiconductor layer and the ONO layer that will act as a channel of the cell transistor. In this embodiment, the through hole 430 is formed to a diameter of 10 ~ 1,000Å.

Referring to FIG. 17, an ONO dielectric layer 440, that is, a blocking layer, a charge trap layer, and a tunneling layer, may be sequentially formed on the inner wall of the through hole 430.

Specifically, a blocking layer is formed on the inner wall of the through hole 430 to prevent the movement of charge from the charge trap layer (not shown) to the control gate electrode. The blocking layer is formed by depositing an oxide film by chemical vapor deposition (CVD), or aluminum oxide (Al ₂ O ₃ ), hafnium oxide (HfO ₂ ), zirconium oxide (ZrO ₂ ), hafnium aluminum oxide (HfAlO), hafnium silicon It may be formed of a high-k material such as oxide (HfSiO). After the blocking layer is formed, rapid thermal annealing may be performed on the semiconductor substrate on which the blocking layer is formed.

Next, a charge trap layer is formed by depositing, for example, a silicon nitride film or a polysilicon film on the blocking layer formed on the inner wall of the through hole 430 to a thickness of 10 to 1,000 Å. The charge trap layer may be deposited by atomic layer deposition (ALD) or chemical vapor deposition (CVD). An oxide film is deposited on the charge trap layer of the inner wall of the through hole 430 to a thickness of 10 to 1,000 Å to form a tunneling layer of the memory cell. When forming the tunneling layer may be performed in an atmosphere containing oxygen and nitrogen at the same time to form an oxynitride (SiON). In addition, after forming the tunneling layer, the film quality may be improved by heat treatment in an NO gas or N ₂ O gas atmosphere.

On the tunneling layer formed on the inner wall of the through hole, a protective film 450 is formed to protect the tunneling layer in the subsequent etching of the ONO dielectric layer. The protective film 450 may be formed of a conductive film, such as a doped polysilicon film, or an insulating film, such as a nitride film, and may be formed to a thickness of 10 to 1,000 Å. When the passivation layer 450 is formed of a conductive layer such as a doped polysilicon layer, the passivation layer 450 may be used as a channel region or a part of the channel region of the memory cell.

Referring to FIG. 18, the passivation layer 450, the tunneling layer, the charge trap layer, and the blocking layer at the bottom of the through-hole are etched to connect the channel region of the source select transistor with the channel region of the memory cell so that the channel region of the source select transistor is etched. Allow exposure. In some cases, an etching process for exposing the channel region of the source select transistor may be performed without forming the passivation layer 450.

For example, an N-type doped silicon film is deposited on the resultant to form the channel region 460 of the memory cell. The channel region 460 of the memory cell is connected to the channel region 370 of the source select transistor. Next, in order to connect the well region of the memory cell with the well region formed in the source select transistor, the doped silicon film at the bottom of the through hole is etched to expose the well region of the source select transistor. Subsequently, the doped silicon film is buried in the center of the through hole to form the well region 470. The well region 470 may be formed by depositing a silicon film doped with a P-type dopant having a conductivity opposite to that of the channel region 460 and the same conductivity as that of the substrate 300. Alternatively, after the silicon film doped with the same conductivity type as the channel region 460 of the memory cell is deposited, it may be formed by silver-to-doped P-type using a doping method such as ion implantation.

Referring to FIG. 19, a drain select transistor for string selection is formed. Specifically, an insulating film 480 for separating the drain select transistor and the memory cell is formed on the resultant through-hole filling. A doped polysilicon film, a metal film, or another conductive material film is formed on the insulating film 480 to a thickness of 10 to 1,000 Å to form the gate conductive layer 490 of the drain select transistor. Subsequently, an insulating film 500 is formed to separate the gate conductive layer 490 of the drain select transistor from the upper conductive layer.

Next, in order to connect the drain select transistor and the memory cell transistor, the conductive layer 490 and the insulating layers 480 and 500 are anisotropically etched to form holes for exposing the channel region of the memory cell transistor. The etching process for forming the hole may be performed by wet etching, dry etching, or a mixture thereof. The hole may be formed to a diameter of 10 to 1,000 mm 3.

A silicon oxide film is deposited on the inner wall of the hole, for example, in a thickness of 10 to 500 Å to form a gate insulating film 510 of the drain select transistor. When forming the gate insulating layer 510 of the drain selection transistor, the oxynitride layer SiON may be formed in an atmosphere containing oxygen and nitrogen at the same time. In addition, after the gate insulating film 510 is formed, the film quality of the gate insulating film may be improved by heat treatment in an NO gas or N ₂ O gas atmosphere.

Next, in order to connect the channel region of the memory cell and the channel region of the drain select transistor, the gate insulating layer 510 is etched to expose the channel region of the memory cell. Before etching the gate insulating film 510, a protective film made of a conductive film such as a polysilicon film is formed on the gate insulating film 510 formed on the inner wall of the hole and then etched to protect the gate insulating film 510 on the sidewall of the hole. Can be. In this case, the conductive film used as the passivation film may be used as part of the channel region or the channel region of the drain select transistor.

The semiconductor layer is formed to fill the hole with the channel region of the memory cell, thereby forming the channel region 520 of the drain select transistor. The semiconductor layer may be formed using, for example, a selective epitaxial growth (SEG) method so that the silicon (Si) film is grown from the channel region of the memory cell in a gas atmosphere containing silicon (Si).

As shown in FIG. 20, the P well 530 may be formed in the channel region similarly to the case of the source select transistor in the case of the drain select transistor.

Next, an etching process for separating the drain select transistors is performed.

Although the present invention has been described in detail with reference to preferred embodiments, the present invention is not limited to the above embodiments, and various modifications may be made by those skilled in the art within the technical spirit of the present invention. Do.

1 is a three-dimensional view showing a flash memory device having a three-dimensional structure according to an embodiment of the present invention.

2 to 11 are cross-sectional views illustrating a method of manufacturing a flash memory device having a three-dimensional structure according to an embodiment of the present invention.

12 is a three-dimensional view showing a flash memory device having a three-dimensional structure according to another embodiment of the present invention.

14 is a three-dimensional view showing a flash memory device having a three-dimensional structure according to another embodiment of the present invention.

15 to 20 are cross-sectional views illustrating a method of manufacturing a flash memory device having a three-dimensional structure according to another embodiment of the present invention.

Claims (16)

Forming a source region in the substrate; Forming a source select transistor connected to the source region on the substrate; Forming gates of a plurality of memory cells by alternately forming an insulating layer and a conductive layer on the substrate on which the source select transistor is formed; Etching the insulating layer and the conductive layer to form a through hole exposing a channel region of the source selection transistor; Forming a charge storage region including a tunneling layer, a charge trap layer, and a blocking layer on an inner wall of the through hole; Forming a protective film on an inner sidewall of the through hole in which the charge storage region is formed; Exposing a channel region of the source select transistor; Filling the through hole with a semiconductor layer to form a channel region of a cell transistor; And And forming a drain select transistor on the cell transistor. The method of claim 1, Forming the source select transistor, Sequentially stacking an insulating layer and a conductive layer on the substrate; Etching the insulating layer and the conductive layer to form a through hole exposing the source region; Forming a gate insulating film on an inner wall of the through hole; Etching the gate insulating film to expose the source region, and And filling the through-holes with a semiconductor layer to form a channel region of a source select transistor. The method of claim 1, And the protective film is formed of a polysilicon film or a nitride film. The method of claim 1, And removing the protective film before filling the through-holes with the semiconductor layer. The method of claim 1, The conductive layer for forming the gate of the memory cell is a method of manufacturing a flash memory device, characterized in that formed of polysilicon or metal. The method of claim 1, In the forming of the tunneling layer, A method of manufacturing a flash memory device comprising depositing a silicon compound in an atmosphere containing oxygen or oxygen and nitrogen. The method of claim 6, After forming the tunneling layer, A method of manufacturing a flash memory device, characterized in that it further comprises the step of heat treatment in NO or N ₂ O atmosphere. Forming a source region in the substrate; Forming an insulating film and a conductive layer on the substrate; Forming a first through hole exposing the source region; Sequentially forming a gate insulating film and a channel region of a source selection transistor on sidewalls of the first through hole; Forming a well in the source region of the region exposed by the first through hole; Filling the first through hole to form a well of a source select transistor; Forming gates of a plurality of memory cells by alternately forming an insulating layer and a conductive layer on the substrate on which the wells of the source selection transistor are formed; Etching the insulating layer and the conductive layer to form a second through hole exposing a channel region of the source selection transistor; Forming a charge storage region including a tunneling layer, a charge trap layer, and a blocking layer on an inner wall of the second through hole; Etching the charge storage region at the bottom of the second through hole to expose the channel region of the source select transistor; Forming a channel region of a memory cell on an inner wall of the second through hole; Filling the second through hole to form a well of a cell transistor; And And forming a drain select transistor on the cell transistor. The method of claim 8, Forming the well in the source region of the region exposed by the first through hole, Opening a region where a well of a source select transistor is to be formed; And doping the open region into a conductivity type opposite to that of the source region. 10. The method of claim 9, Doping the open region with a conductivity opposite to the source region, Implanting a dopant of a conductivity type opposite to that of the source region into the open region; A method of manufacturing a flash memory device comprising overetching a substrate in an open area. The method of claim 8, Forming a well of the source select transistor, And depositing a doped silicon film of a first conductivity type or injecting a dopant of a first conductivity type after the deposition of an undoped silicon film. The method of claim 8, Forming a tunneling layer on the inner wall of the second through hole, A method of manufacturing a flash memory device comprising depositing a silicon compound in an atmosphere containing oxygen or oxygen and nitrogen. The method of claim 12, After forming the tunneling layer, A method of manufacturing a flash memory device, characterized in that it further comprises the step of heat treatment in NO or N ₂ O atmosphere. The method of claim 8, After forming a charge storage region on the inner wall of the second through hole, And forming a passivation layer on an inner wall of the second through hole in which the charge storage region is formed. The method of claim 14, And the protective film is formed of a polysilicon film or a nitride film. The method of claim 8, Forming the well of the cell transistor, And depositing a doped silicon film of a first conductivity type or injecting a dopant of a first conductivity type after the deposition of an undoped silicon film.

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